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Diabetologia. 2018 Aug;61(8):1734-1747. doi: 10.1007/s00125-018-4628-9. Epub 2018 May 23.

Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial.

Author information

1
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 5th Floor, Medical Science Building (MSB), 1 Kings College Circle, Toronto, ON, M5S 1A8, Canada. david.jenkins@utoronto.ca.
2
Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada. david.jenkins@utoronto.ca.
3
Clinical Nutrition and Risk Factor Modification Centre, St Michael's Hospital, Toronto, ON, Canada. david.jenkins@utoronto.ca.
4
Division of Endocrinology and Metabolism, St Michael's Hospital, Toronto, ON, Canada. david.jenkins@utoronto.ca.
5
Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, ON, Canada. david.jenkins@utoronto.ca.
6
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 5th Floor, Medical Science Building (MSB), 1 Kings College Circle, Toronto, ON, M5S 1A8, Canada.
7
Clinical Nutrition and Risk Factor Modification Centre, St Michael's Hospital, Toronto, ON, Canada.
8
College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada.
9
School of Nutrition, Institute of Nutrition and Functional Foods, Laval University, Quebec City, QC, Canada.
10
Division of Family and Community Medicine, St Michael's Hospital, Toronto, ON, Canada.
11
Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, ON, Canada.
12
Department of Mathematics and Statistics, University of Windsor, Windsor, ON, Canada.
13
Division of Endocrinology and Metabolism, St Michael's Hospital, Toronto, ON, Canada.
14
Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, ON, Canada.
15
Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.

Abstract

AIMS/HYPOTHESIS:

In line with current advice, we assessed the effect of replacing carbohydrate consumption with mixed nut consumption, as a source of unsaturated fat, on cardiovascular risk factors and HbA1c in type 2 diabetes. The data presented here are from a paper that was retracted at the authors' request ( https://doi.org/10.2337/dc16-rt02 ) owing to lack of adjustment for repeated measures in the same individual. Our aim, therefore, was to fix the error and add new complementary data of interest, including information on clotting factors and LDL particle size.

METHODS:

A total of 117 men and postmenopausal women with type 2 diabetes who were taking oral glucose-lowering agents and with HbA1c between 47.5 and 63.9 mmol/mol (6.5-8.0%) were randomised after stratification by sex and baseline HbA1c in a parallel design to one of three diets for 3 months: (1) 'full-dose nut diet' (n = 40): a diet with 2.0 MJ (477 kcal) per 8.4 MJ (2000 kcal) energy provided as mixed nuts (75 g/day); (2) 'full-dose muffin diet' (n = 39): a diet with 1.97 MJ (471 kcal) per 8.4 MJ (2000 kcal) energy provided as three whole-wheat muffins (188 g/day), with a similar protein content to the nuts, and the same carbohydrate-derived energy content as the monounsaturated fatty acid-derived energy content in the nuts; or (3) 'half-dose nut diet' (n = 38): a diet with 1.98 MJ (474 kcal) per 8.4 MJ (2000 kcal) energy provided as half portions of both the nuts and muffins. The primary outcome was change in HbA1c. The study was carried out in a hospital clinical research centre and concluded in 2008. Only the statistician, study physicians and analytical technicians could be blinded to the group assessment.

RESULTS:

A total of 108 participants had post-intervention data available for analysis (full-dose nut group, n = 40; full-dose muffin group, n = 35; half-dose nut group, n = 33). Compared with the full-dose muffin diet, the full-dose nut diet provided 9.2% (95% CI 7.1, 11.3) greater total energy intake from monounsaturated fat. The full-dose nut diet (median intake, 75 g/day) also reduced HbA1c compared with the full-dose muffin diet by -2.0 mmol/mol (95% CI -3.8, -0.3 mmol/mol) (-0.19% [95% CI -0.35%, -0.02%]), (p = 0.026). Estimated cholesterol levels in LDL particles with a diameter <255 ångström [LDL-c<255Å]) and apolipoprotein B were also significantly decreased after the full-dose nut diet compared with the full-dose muffin diet. According to the dose response, the full-dose nut diet is predicted to reduce HbA1c (-2.0 mmol/mol [-0.18%]; p = 0.044), cholesterol (-0.25 mmol/l; p = 0.022), LDL-cholesterol (-0.23 mmol/l; p = 0.019), non-HDL-cholesterol (-0.26 mmol/l; p = 0.020), apolipoprotein B (-0.06 g/l, p = 0.013) and LDL-c<255Å (-0.42 mmol/l; p < 0.001). No serious study-related adverse events occurred, but one participant on the half-dose nut diet was hospitalised for atrial fibrillation after shovelling snow.

CONCLUSIONS/INTERPRETATION:

Nut intake as a replacement for carbohydrate consumption improves glycaemic control and lipid risk factors in individuals with type 2 diabetes.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT00410722 FUNDING: The study was funded by the International Tree Nut Council Nutrition Research and Education Foundation, the Peanut Institute, Loblaw Companies and the Canada Research Chairs Program of the Government of Canada.

KEYWORDS:

Blood lipids; Clotting factors; Glycaemic control; Nuts; Type 2 diabetes

PMID:
29789878
PMCID:
PMC6061153
DOI:
10.1007/s00125-018-4628-9
[Indexed for MEDLINE]
Free PMC Article

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